This invention relates to torque converter turbines, and more particularly, to such turbines having molded hydrofoil blades.
Thin sheet metal bladed turbines provide a substantially diverging-converging flow area from the inlet of the turbine to the exit. Prior art hydrofoil blade shapes have achieved better flow area distribution but have a significantly reduced converter capacity. Thus, the industry has, for the most part, continued to use thin sheet metal blades in torque converters and impellers while using cast hydrofoil shapes in the stator. Another reason was that they did not have a manufacturing process inexpensive enough for the automotive applications. Now we have the "lost-core" plastic molded process.
The bladed turbine is sensitive to the direction of flow at the inlet. As is well known, the angle of inlet flow relative to the leading edge of the turbine blade varies with the speed ratio between the turbine and the impeller. The hydrofoil blade with round leading edge is less sensitive to the flow direction entering the turbine. Therefore, the hydrofoil turbine has less incidence loss than the sheet metal turbine. However, the improved capacity and the reduced manufacturing cost in thin sheet metal bladed devices outweigh the disadvantage which accompanies the round hydrofoil leading edge. In other words, the thin sheet metal bladed turbines have been found to be as effective as the cast hydrofoil bladed turbines in the prior art.